A typical miniature diaphragm pump includes a base, and a diaphragm mounted to one side of the base. The miniature diaphragm pump defines an air inlet chamber in the base and further defines an air exhaust chamber outside the base. The air exhaust chamber is separate from the air inlet chamber. The diaphragm includes multiple air bags received in the air inlet chamber. Each air bag defines a pump chamber therein, and the pump chamber communicates with the air inlet chamber and the air exhaust chamber via a first passage and a second passage, respectively. A first valve is formed on the diaphragm aligned with the first passage, to thereby join or cut the communication between the pump chamber and the air inlet chamber. A second valve is aligned with the second passage, to thereby join or cut the communication between the pump chamber and the air exhaust chamber. The first passage is formed as a through hole in the base and provides a shortest path for the air intake.
The air bags are driven by an eccentric assembly, and the eccentric assembly is driven by a motor. When the motor works, the air bags are caused to be expanded or compressed due to the movement of the eccentric assembly, thereby sucking air from the air inlet chamber or exhausting air into the air exhaust chamber. However, during the air intake portion of the pumping cycle, undesired audible noise raises in the miniature diaphragm pump.
Therefore, there is a desire for an improved diaphragm pump, especially one which can be made in a small or miniature size.